Master Brigsby would be lying if he said he wasn't extremely agitated by the counter that Rui had come up with to negate his light beams.
His light beams were an extremely powerful and lethal offense that was normally limited to the Sage Realm. He was perhaps the only Master who had harnessed light at all, let alone to such a degree. With that out of the way, he was essentially left toothless due to how much he had invested in these attacks.
They were extraordinarily fast and could not be dodged after they were launched. This principle had allowed him to land his attacks with an unprecedented level of success. On top of that, by continuously refining the intensity of his light attacks, he could turn them into an instant-kill technique that killed any Master any time where they stood.
He also normally distanced himself from his opponents, making it impossible to detect his attacks ahead of time.